| Project/Area Number |
12358008
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Environmental dynamic analysis
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| Research Institution | The University of Tokyo |
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Principal Investigator |
KOMATSU Teruhisa The University of Tokyo, Ocean Research Institute, Associate Professor, 海洋研究所, 助教授 (60215390)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAOKA Masahiro Chiba University, Graduate School of Science and Technology, Associate Professor, 大学院・自然科学研究科, 助教授 (90260520)
TAIRA Asahiko Japan Marine Science and Technology Center, Ocean Drilling 21^<st> Century, Director (Researcher), 深海地球ドリリング計画推進本部, 部長(研究職) (50112272)
SUGIMOTO Takashige The University of Tokyo, Ocean Research Institute, Professor, 海洋研究所, 教授 (40004428)
TATSUKAWA Kenichi The University of Tokyo, Ocean Research Institute, Research Associate, 海洋研究所, 助手 (20013584)
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| Project Period (FY) |
2000 – 2002
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| Keywords | acoustic survey / classification of substrate / multibeam sonar / sea bottom / coastal environment / seagrass / seaweed beds / mapping / bottom topography |
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| Research Abstract |
This study aimed to develop portable and small-size three-dimensional mapping system of marine organisms and environment on the sea bottom. The developed system can map precise coastal bottom topography acquiring accurate ship position, measuring bottom depths, substrate and distribution of benthic organisms such as seagrass with multibeam sonar, displaying bottom profile in real time. Since echosounders scan bottom depth with only short swath width, bottom topography must be interpolated between transects because of wide interval. It can sound three-dimensional form of bottom surface in aide of the multibeam sonar with wide swath width without interpolation classifying bottom substrate and measuring biomass of seagrass/seaweeds as a remote sensing system. The system also localizes not only the ship position but also bottom positions of ultrasound beams on the bottom by using accurate D-GPS, gyrocompass and motion sensor. We developed method mapping bottom topography and substrate by processing data with GIS. Field researches were conducted around Otsuchi Bay, Aburatsubo Bay and seamount in southern Tunisia. Since the research in Otsuchi Bay targeted seagrass beds, we made studies on ecology and biomass of seagrass as a sea truth survey. Before development of mapping software, we made researches on change in intertidal ecosystem polluted by the Nakhodka oil spill accident, and management and conservation of coastal areas as a research for GIS applying to studies on fisheries and oceanography. Conventional methods to measure bottom substrate and biomass of benthic organisms on the sea bottom are diving along a line transect or core sampling that are not efficient. It was verified that the developed system could map precisely bottom environment on the sea bottom surface with ecosystems varying in a horizontal scale of 1 to 100 m. The system contributes to not only scientific but also social domains for practice of coastal zone management.
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